Longitudinal support of mechanical filter



Nov. 2, 1954 M. l.. DoELz 2,693,579

LONGITUDINAL SUPPORT OF MECHANICAL FILTER Filed April 2l, 1952 j 1.9 "if J6 6 VI 2.9 A u K 24 f- 43g@ .is Z6 z 1J a lo INVENTOR.

M51 V/a/ l. Datz z Byaw y 2,693,579 Patented Nov. 2, 1954 LONGITUDINAL SUPPORT F MECHANICAL FILTER Melvin L. Doelz, Glendale, Calif., assignor to Collins Radio Company, Cedar Rapids, Iowa, a corporation of Iowa Application April 21, 1952, Serial No. 283,340

Claims. (Cl. 333--71) This invention relates in general to electromechanical lters and in particular to a new and novel assembly of an electromechanical filter.

The co-pending application of Melvin L. Doelz, entitled Mechanical Filters, Serial Number 248,011, filed September 24, 1951, discloses an electromechanical lter wherein a plurality of discs are coupled together by longitudinal wires connected to their peripheries. A magnetostrictive driving wire is connected to a first disc and driven by a signal source and an output magnetostrictive wire is connected to the last disc and coupled to a magnetostrictive output means. Applicant has found that this type of electromechanical filter has very desirable characteristics in terms of high performance in a small space and ease of construction. The present invention relates to means for mechanically supporting the filter made according to the principles of the referenced application so as to minimize damping and detuning of the vibrating discs.

It is an object of this invention, therefore, to provide a mounting means for an electromechanical filter wherein the filter is mounted and held firmly Without damping or interfering with the oscillations of the disc.

Another object of this invention is to provide a compact electromechanical filter which firmly supports the vibrating discs and protects the driving wires with a suitable cover member.

Further features, objects and advantages of this invention will become apparent from the following description and claims when read in view of the drawings, in which:

Figure 1 is a top view of the electromechanical filter of this invention with the top cover removed;

Figure 2 is a side elevational View taken on line 22 of Figure 1 and shows the cover;

Figure 3 is a partial bottom view;

Figure 4 is a sectional View taken on line 4 4 of Figure 2; and

Figure 5 is a sectional view taken on line 5 5 of Figure 1.

Figure 1 is a view of the filter with the top cover removed and illustrates a base plate upon which are mounted a pair of stand-offs 11 and 12, respectively. As best shown in Figure 2, the stand-offs 11 and 12 are each formed in two parts with lower parts 13 and 14, respectively, and top parts 16 and 17, respectively. The lower parts 13 and 14 are attached to the base plate 10 by set screws 18 and the top parts 16 and 17 are attached by set screws 19 to the lower parts.

At the junction between the upper and lower parts of the stand-offs 11 and 12 are formed circular openings lined with a suitable gasketing material through which cylinders 21 and 22 extend. These cylinders are clamped by the stand-offs 11 and 12. The cylinders are hollow as shown in Figure 5 and contain therein a magnetic driving coil 23 which has output leads 24 and 26 which are attached, respectively, to output contacts 27 and 28. Contacts 27 and 28 extend through the base plate 10.

Polarizing magnets 29 and 31, respectively, are supported by the standoffs 11 and 12 immediately above the cylinders 21 and 22. The cylinders 21 and 22 may ige made of a non-magnetic material, as for example rass. f

Mounted between the cylinders 21 and 22 is the vibrating filter assembly comprising a plurality of active discs 32 and a pair of end discs 33 and 34, respectively.

The discs 32, 33, and 34 are connected together by longitudinal coupling wires 36 which are attached to the peripheries of the disc. The discs are spaced equidistant apart.

As pointed out in the Doelz application, Serial Number 248,011, the thickness and diameter of the discs determines the resonant frequency of the filter.

The cylinders 21 and 22 are formed with openings designated as 37 in Figure 4 and the end discs 33 and 34 are received therein. The discs are firmly attached to the cylinders by welding.

Thus, the end discs 33 and 34, respectively, are firmly supported by the cylinders 21 and 22 and do not comprise a part of the vibrating system. The spacing between the disc 33 and the adjacent active disc is substantially the same as that between a pair of active discs. The short lengths of coupling wire joining the active filter structure and the inactive end discs act as springs interspaced between the vibrating filter structure and the fixed mounting structure. As best shown in Figure 5, an opening 38 is formed through the lower edge of the discs 33 and 34 which is supported within the confines of the cylinders 21 and 22. A driving rod 39 extends through the opening 38 and is attached to the periphery of the actvsdisc 32. The rod 39 extends through the driving co1 The active disc 32 at the opposite end of the filter also has a driving wire 41 which is shown in Figure 2 that extends within the confines of the cylinder 22 and through a second driving coil contained therein. The output leads of the driving coil within the cylinder 22 are designated as 42 and 43, respectively, and are connected to contacts 44 and 46, respectively, which extend through the base plate 10.

A cover member 47 is generally rectangular in shape and has downwardly extending sides 48. It may be placed over the filter assembly and firmly attached to the base plate 10, as for example by crimping or soldering. The filter unit may be hermetically sealed if desired.

Attached to the base plate are a pair of mounting pins 49 and 51 which may be used to attach the filter assembly to a chassis. Input and output leads may be connected to the terminals 27, 28, 44 and 46.

It is seen that this invention provides a supporting means for an electromechanical filter wherein the active discs 32 are firmly supported without interfering with the mechanical vibrations of the system. The apparatus is particularly useful as a band pass filter, as for example in an intermediate frequency stage Where it might be tuned to 455 kilocycles, for example. The apparatus shown in Figure 2 is substantially the same length as a cigarette at 455 kilocycles and is thus very compact. Electrical filters do not compare with the frequency characteristics of this filter because of the extremely high resonator Q which is obtainable.

Although this invention has been described with respect to a particular embodiment thereof, it is not to be so limited as changes and modications may be made therein which are within the full intended scope of the invention, as defined by the appended claims.

I claim:

1. An electrical mechanical filter comprising, a base plate, a magnetostrictive driving means mounted on said ba'se plate, a magnetostrictive output means mounted on said base plate, a plurality of discs, a plurality of longitudinal coupling wires connected to the edges of said discs to hold them in an assembled relationship, one of the end discs mechanically connected to said magnetostrlctive driving means, the other end disc mechanically connected to the magnetostrictive output means, openings formed in the end discs, a driving rod of said magnetostrictive driving means extending through the opening in one of said discs and connected to the second disc, and an output driving wire extending from the magnetostrictlve output means through the opening formed in the other end disc and connected to the disc adjacent thereto.

2. A magnetostrictive filter comprising, a base plate, a magnetostrictive driving means attached to said base plate, a magnetostrictive output means connected to said base plate, a first disc attached to the magnetostrictive mput means, a second disc supported parallel to the first d1sc 'by the magnetostrictive output means, a plurality of longitudinal coupling wires extending between the edges of the rst and' second discs, a plurality of discs spaced parallel between the'rst'and seconddiscs andattachedto the coupling wires, openings formed in the first and second discs, a driving Wire extending from the magnetostrictivetdrivingfmeans throughthe opening: formedin the first disc and connected to the disc adjacent saidrst disc and an outputdrivingz-Wirerextending fromltheoutvpute magnetostrictive'- means,l vthrough t the opening formed in the secondI discs` and attached tothe discadjacent thereto;

3. Means foi-.supporting an? electromechanical lter comprising, aplurality of'discsA mounted parallel to each other, a plurality of coupling wires attachedxto the-edges offall thediscs to,`y hold them` in an'v assembled relationship, a magnetostrictiveiinput'.means, amechanical supportl supportingzrst end disc and saidmagnetostrictive input means, a drivingfwire extending,from;the magnetostrictive inputmeans and=connectedto the disc adjacent the: first'. endy disc, a magnetostrictive outputV means, a secondmechanicaLsupport supporting said output means and thevother end disc, and an output' coupling wire extendingfrom said outputi magnetostrictive means. and connectedIto the disc adjacent ,the second end disc.

4. An, electromechanical lter comprising,` a plurality of, discs mountedparallel to eachother, a plurality of couplingwires attached to'theedges of saiddisc to hold themina,predeterminedassembly, first supporting means attached to one end disc, second supporting means attached to-the-opposite enddisc, a magnetostrictive input means Vwith a driving wire extending therefrom and con- 30 nected 'tothe disc adjacent theone-end disc, and a magnetostrictiveroutput means'with anoutput'wire extending therefrom and connected to the disc adjacent the oppositev end disc.y

5. An electromechanicallter comprising, a base plate, a pair of stand-offs mounted on said base plate, a pair of cylinders supported, respectively, by said stand-offs, an input magnetostrictive coupling means mounted within said first cylinder, a magnetostrictive output means mounted=in said second cylinder, a driving wire extending from said input means, a'driving wire extending from said output means, a plurality of discs, a plurality of coupling wires attached to the peripheries of said discs toy support them inl an assembly, a rst end disc connected to said lrst cylinder, a second end disc connected to the second cylinder, openings formed in the end discs, the input driving wire extending through the opening formed in the rst enddisc and attached to the edge of the second disc, the output driving wire extending through the opening formed in the other end disc and attached to the edge of the disc adjacent-thereto, and a cover memberattached to saidrbase plate so as to enclose said electromechanical ilter.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,678,116 Harrison July 24, 1928 FOREIGN PATENTS Number Country Date 706,272 Germany May 22, 1941 

